diff --git a/.github/workflows/pr-labeler.yml b/.github/workflows/pr-labeler.yml
index feabf65340..e89597a5cc 100644
--- a/.github/workflows/pr-labeler.yml
+++ b/.github/workflows/pr-labeler.yml
@@ -17,7 +17,7 @@ jobs:
           repoToken: "${{ secrets.GITHUB_TOKEN }}"
           commentOnDirty: "This pull request has conflicts, please resolve those before we can evaluate the pull request."
       - name: Apply Size Label
-        if: ${{ github.ref != 'refs/heads/master' }}
+        if: (github.event_name == 'pull_request_target' && github.head_ref != 'refs/heads/master')
         uses: pascalgn/size-label-action@v0.5.0
         env:
           GITHUB_TOKEN: "${{ secrets.GITHUB_TOKEN }}"